On Tue, 2013-05-21 at 13:33 +1000, Alexey Kardashevskiy wrote:
> VFIO implements platform independent stuff such as
> a PCI driver, BAR access (via read/write on a file descriptor
> or direct mapping when possible) and IRQ signaling.
>
> The platform dependent part includes IOMMU initialization
> and handling. This implements an IOMMU driver for VFIO
> which does mapping/unmapping pages for the guest IO and
> provides information about DMA window (required by a POWER
> guest).
>
> Cc: David Gibson <david@xxxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Alexey Kardashevskiy <aik@xxxxxxxxx>
> Signed-off-by: Paul Mackerras <paulus@xxxxxxxxx>
Acked-by: Alex Williamson <alex.williamson@xxxxxxxxxx>
> ---
> Documentation/vfio.txt | 63 ++++++
> drivers/vfio/Kconfig | 6 +
> drivers/vfio/Makefile | 1 +
> drivers/vfio/vfio.c | 1 +
> drivers/vfio/vfio_iommu_spapr_tce.c | 377 +++++++++++++++++++++++++++++++++++
> include/uapi/linux/vfio.h | 34 ++++
> 6 files changed, 482 insertions(+)
> create mode 100644 drivers/vfio/vfio_iommu_spapr_tce.c
>
> diff --git a/Documentation/vfio.txt b/Documentation/vfio.txt
> index 8eda363..c55533c 100644
> --- a/Documentation/vfio.txt
> +++ b/Documentation/vfio.txt
> @@ -283,6 +283,69 @@ a direct pass through for VFIO_DEVICE_* ioctls. The read/write/mmap
> interfaces implement the device region access defined by the device's
> own VFIO_DEVICE_GET_REGION_INFO ioctl.
>
> +
> +PPC64 sPAPR implementation note
> +-------------------------------------------------------------------------------
> +
> +This implementation has some specifics:
> +
> +1) Only one IOMMU group per container is supported as an IOMMU group
> +represents the minimal entity which isolation can be guaranteed for and
> +groups are allocated statically, one per a Partitionable Endpoint (PE)
> +(PE is often a PCI domain but not always).
> +
> +2) The hardware supports so called DMA windows - the PCI address range
> +within which DMA transfer is allowed, any attempt to access address space
> +out of the window leads to the whole PE isolation.
> +
> +3) PPC64 guests are paravirtualized but not fully emulated. There is an API
> +to map/unmap pages for DMA, and it normally maps 1..32 pages per call and
> +currently there is no way to reduce the number of calls. In order to make things
> +faster, the map/unmap handling has been implemented in real mode which provides
> +an excellent performance which has limitations such as inability to do
> +locked pages accounting in real time.
> +
> +So 3 additional ioctls have been added:
> +
> + VFIO_IOMMU_SPAPR_TCE_GET_INFO - returns the size and the start
> + of the DMA window on the PCI bus.
> +
> + VFIO_IOMMU_ENABLE - enables the container. The locked pages accounting
> + is done at this point. This lets user first to know what
> + the DMA window is and adjust rlimit before doing any real job.
> +
> + VFIO_IOMMU_DISABLE - disables the container.
> +
> +
> +The code flow from the example above should be slightly changed:
> +
> + .....
> + /* Add the group to the container */
> + ioctl(group, VFIO_GROUP_SET_CONTAINER, &container);
> +
> + /* Enable the IOMMU model we want */
> + ioctl(container, VFIO_SET_IOMMU, VFIO_SPAPR_TCE_IOMMU)
> +
> + /* Get addition sPAPR IOMMU info */
> + vfio_iommu_spapr_tce_info spapr_iommu_info;
> + ioctl(container, VFIO_IOMMU_SPAPR_TCE_GET_INFO, &spapr_iommu_info);
> +
> + if (ioctl(container, VFIO_IOMMU_ENABLE))
> + /* Cannot enable container, may be low rlimit */
> +
> + /* Allocate some space and setup a DMA mapping */
> + dma_map.vaddr = mmap(0, 1024 * 1024, PROT_READ | PROT_WRITE,
> + MAP_PRIVATE | MAP_ANONYMOUS, 0, 0);
> +
> + dma_map.size = 1024 * 1024;
> + dma_map.iova = 0; /* 1MB starting at 0x0 from device view */
> + dma_map.flags = VFIO_DMA_MAP_FLAG_READ | VFIO_DMA_MAP_FLAG_WRITE;
> +
> + /* Check here is .iova/.size are within DMA window from spapr_iommu_info */
> +
> + ioctl(container, VFIO_IOMMU_MAP_DMA, &dma_map);
> + .....
> +
> -------------------------------------------------------------------------------
>
> [1] VFIO was originally an acronym for "Virtual Function I/O" in its
> diff --git a/drivers/vfio/Kconfig b/drivers/vfio/Kconfig
> index 7cd5dec..b464687 100644
> --- a/drivers/vfio/Kconfig
> +++ b/drivers/vfio/Kconfig
> @@ -3,10 +3,16 @@ config VFIO_IOMMU_TYPE1
> depends on VFIO
> default n
>
> +config VFIO_IOMMU_SPAPR_TCE
> + tristate
> + depends on VFIO && SPAPR_TCE_IOMMU
> + default n
> +
> menuconfig VFIO
> tristate "VFIO Non-Privileged userspace driver framework"
> depends on IOMMU_API
> select VFIO_IOMMU_TYPE1 if X86
> + select VFIO_IOMMU_SPAPR_TCE if PPC_POWERNV
> help
> VFIO provides a framework for secure userspace device drivers.
> See Documentation/vfio.txt for more details.
> diff --git a/drivers/vfio/Makefile b/drivers/vfio/Makefile
> index 2398d4a..72bfabc 100644
> --- a/drivers/vfio/Makefile
> +++ b/drivers/vfio/Makefile
> @@ -1,3 +1,4 @@
> obj-$(CONFIG_VFIO) += vfio.o
> obj-$(CONFIG_VFIO_IOMMU_TYPE1) += vfio_iommu_type1.o
> +obj-$(CONFIG_VFIO_IOMMU_SPAPR_TCE) += vfio_iommu_spapr_tce.o
> obj-$(CONFIG_VFIO_PCI) += pci/
> diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
> index 295c48f..a819604 100644
> --- a/drivers/vfio/vfio.c
> +++ b/drivers/vfio/vfio.c
> @@ -1428,6 +1428,7 @@ static int __init vfio_init(void)
> * drivers.
> */
> request_module_nowait("vfio_iommu_type1");
> + request_module_nowait("vfio_iommu_spapr_tce");
>
> return 0;
>
> diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c b/drivers/vfio/vfio_iommu_spapr_tce.c
> new file mode 100644
> index 0000000..bdae7a0
> --- /dev/null
> +++ b/drivers/vfio/vfio_iommu_spapr_tce.c
> @@ -0,0 +1,377 @@
> +/*
> + * VFIO: IOMMU DMA mapping support for TCE on POWER
> + *
> + * Copyright (C) 2013 IBM Corp. All rights reserved.
> + * Author: Alexey Kardashevskiy <aik@xxxxxxxxx>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + * Derived from original vfio_iommu_type1.c:
> + * Copyright (C) 2012 Red Hat, Inc. All rights reserved.
> + * Author: Alex Williamson <alex.williamson@xxxxxxxxxx>
> + */
> +
> +#include <linux/module.h>
> +#include <linux/pci.h>
> +#include <linux/slab.h>
> +#include <linux/uaccess.h>
> +#include <linux/err.h>
> +#include <linux/vfio.h>
> +#include <asm/iommu.h>
> +#include <asm/tce.h>
> +
> +#define DRIVER_VERSION "0.1"
> +#define DRIVER_AUTHOR "aik@xxxxxxxxx"
> +#define DRIVER_DESC "VFIO IOMMU SPAPR TCE"
> +
> +static void tce_iommu_detach_group(void *iommu_data,
> + struct iommu_group *iommu_group);
> +
> +/*
> + * VFIO IOMMU fd for SPAPR_TCE IOMMU implementation
> + *
> + * This code handles mapping and unmapping of user data buffers
> + * into DMA'ble space using the IOMMU
> + */
> +
> +/*
> + * The container descriptor supports only a single group per container.
> + * Required by the API as the container is not supplied with the IOMMU group
> + * at the moment of initialization.
> + */
> +struct tce_container {
> + struct mutex lock;
> + struct iommu_table *tbl;
> + bool enabled;
> +};
> +
> +static int tce_iommu_enable(struct tce_container *container)
> +{
> + int ret = 0;
> + unsigned long locked, lock_limit, npages;
> + struct iommu_table *tbl = container->tbl;
> +
> + if (!container->tbl)
> + return -ENXIO;
> +
> + if (!current->mm)
> + return -ESRCH; /* process exited */
> +
> + if (container->enabled)
> + return -EBUSY;
> +
> + /*
> + * When userspace pages are mapped into the IOMMU, they are effectively
> + * locked memory, so, theoretically, we need to update the accounting
> + * of locked pages on each map and unmap. For powerpc, the map unmap
> + * paths can be very hot, though, and the accounting would kill
> + * performance, especially since it would be difficult to impossible
> + * to handle the accounting in real mode only.
> + *
> + * To address that, rather than precisely accounting every page, we
> + * instead account for a worst case on locked memory when the iommu is
> + * enabled and disabled. The worst case upper bound on locked memory
> + * is the size of the whole iommu window, which is usually relatively
> + * small (compared to total memory sizes) on POWER hardware.
> + *
> + * Also we don't have a nice way to fail on H_PUT_TCE due to ulimits,
> + * that would effectively kill the guest at random points, much better
> + * enforcing the limit based on the max that the guest can map.
> + */
> + down_write(¤t->mm->mmap_sem);
> + npages = (tbl->it_size << IOMMU_PAGE_SHIFT) >> PAGE_SHIFT;
> + locked = current->mm->locked_vm + npages;
> + lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
> + if (locked > lock_limit && !capable(CAP_IPC_LOCK)) {
> + pr_warn("RLIMIT_MEMLOCK (%ld) exceeded\n",
> + rlimit(RLIMIT_MEMLOCK));
> + ret = -ENOMEM;
> + } else {
> +
> + current->mm->locked_vm += npages;
> + container->enabled = true;
> + }
> + up_write(¤t->mm->mmap_sem);
> +
> + return ret;
> +}
> +
> +static void tce_iommu_disable(struct tce_container *container)
> +{
> + if (!container->enabled)
> + return;
> +
> + container->enabled = false;
> +
> + if (!container->tbl || !current->mm)
> + return;
> +
> + down_write(¤t->mm->mmap_sem);
> + current->mm->locked_vm -= (container->tbl->it_size <<
> + IOMMU_PAGE_SHIFT) >> PAGE_SHIFT;
> + up_write(¤t->mm->mmap_sem);
> +}
> +
> +static void *tce_iommu_open(unsigned long arg)
> +{
> + struct tce_container *container;
> +
> + if (arg != VFIO_SPAPR_TCE_IOMMU) {
> + pr_err("tce_vfio: Wrong IOMMU type\n");
> + return ERR_PTR(-EINVAL);
> + }
> +
> + container = kzalloc(sizeof(*container), GFP_KERNEL);
> + if (!container)
> + return ERR_PTR(-ENOMEM);
> +
> + mutex_init(&container->lock);
> +
> + return container;
> +}
> +
> +static void tce_iommu_release(void *iommu_data)
> +{
> + struct tce_container *container = iommu_data;
> +
> + WARN_ON(container->tbl && !container->tbl->it_group);
> + tce_iommu_disable(container);
> +
> + if (container->tbl && container->tbl->it_group)
> + tce_iommu_detach_group(iommu_data, container->tbl->it_group);
> +
> + mutex_destroy(&container->lock);
> +
> + kfree(container);
> +}
> +
> +static long tce_iommu_ioctl(void *iommu_data,
> + unsigned int cmd, unsigned long arg)
> +{
> + struct tce_container *container = iommu_data;
> + unsigned long minsz;
> + long ret;
> +
> + switch (cmd) {
> + case VFIO_CHECK_EXTENSION:
> + return (arg == VFIO_SPAPR_TCE_IOMMU) ? 1 : 0;
> +
> + case VFIO_IOMMU_SPAPR_TCE_GET_INFO: {
> + struct vfio_iommu_spapr_tce_info info;
> + struct iommu_table *tbl = container->tbl;
> +
> + if (WARN_ON(!tbl))
> + return -ENXIO;
> +
> + minsz = offsetofend(struct vfio_iommu_spapr_tce_info,
> + dma32_window_size);
> +
> + if (copy_from_user(&info, (void __user *)arg, minsz))
> + return -EFAULT;
> +
> + if (info.argsz < minsz)
> + return -EINVAL;
> +
> + info.dma32_window_start = tbl->it_offset << IOMMU_PAGE_SHIFT;
> + info.dma32_window_size = tbl->it_size << IOMMU_PAGE_SHIFT;
> + info.flags = 0;
> +
> + if (copy_to_user((void __user *)arg, &info, minsz))
> + return -EFAULT;
> +
> + return 0;
> + }
> + case VFIO_IOMMU_MAP_DMA: {
> + struct vfio_iommu_type1_dma_map param;
> + struct iommu_table *tbl = container->tbl;
> + unsigned long tce, i;
> +
> + if (!tbl)
> + return -ENXIO;
> +
> + BUG_ON(!tbl->it_group);
> +
> + minsz = offsetofend(struct vfio_iommu_type1_dma_map, size);
> +
> + if (copy_from_user(¶m, (void __user *)arg, minsz))
> + return -EFAULT;
> +
> + if (param.argsz < minsz)
> + return -EINVAL;
> +
> + if (param.flags & ~(VFIO_DMA_MAP_FLAG_READ |
> + VFIO_DMA_MAP_FLAG_WRITE))
> + return -EINVAL;
> +
> + if ((param.size & ~IOMMU_PAGE_MASK) ||
> + (param.vaddr & ~IOMMU_PAGE_MASK))
> + return -EINVAL;
> +
> + /* iova is checked by the IOMMU API */
> + tce = param.vaddr;
> + if (param.flags & VFIO_DMA_MAP_FLAG_READ)
> + tce |= TCE_PCI_READ;
> + if (param.flags & VFIO_DMA_MAP_FLAG_WRITE)
> + tce |= TCE_PCI_WRITE;
> +
> + ret = iommu_tce_put_param_check(tbl, param.iova, tce);
> + if (ret)
> + return ret;
> +
> + for (i = 0; i < (param.size >> IOMMU_PAGE_SHIFT); ++i) {
> + ret = iommu_put_tce_user_mode(tbl,
> + (param.iova >> IOMMU_PAGE_SHIFT) + i,
> + tce);
> + if (ret)
> + break;
> + tce += IOMMU_PAGE_SIZE;
> + }
> + if (ret)
> + iommu_clear_tces_and_put_pages(tbl,
> + param.iova >> IOMMU_PAGE_SHIFT, i);
> +
> + iommu_flush_tce(tbl);
> +
> + return ret;
> + }
> + case VFIO_IOMMU_UNMAP_DMA: {
> + struct vfio_iommu_type1_dma_unmap param;
> + struct iommu_table *tbl = container->tbl;
> +
> + if (WARN_ON(!tbl))
> + return -ENXIO;
> +
> + minsz = offsetofend(struct vfio_iommu_type1_dma_unmap,
> + size);
> +
> + if (copy_from_user(¶m, (void __user *)arg, minsz))
> + return -EFAULT;
> +
> + if (param.argsz < minsz)
> + return -EINVAL;
> +
> + /* No flag is supported now */
> + if (param.flags)
> + return -EINVAL;
> +
> + if (param.size & ~IOMMU_PAGE_MASK)
> + return -EINVAL;
> +
> + ret = iommu_tce_clear_param_check(tbl, param.iova, 0,
> + param.size >> IOMMU_PAGE_SHIFT);
> + if (ret)
> + return ret;
> +
> + ret = iommu_clear_tces_and_put_pages(tbl,
> + param.iova >> IOMMU_PAGE_SHIFT,
> + param.size >> IOMMU_PAGE_SHIFT);
> + iommu_flush_tce(tbl);
> +
> + return ret;
> + }
> + case VFIO_IOMMU_ENABLE:
> + mutex_lock(&container->lock);
> + ret = tce_iommu_enable(container);
> + mutex_unlock(&container->lock);
> + return ret;
> +
> +
> + case VFIO_IOMMU_DISABLE:
> + mutex_lock(&container->lock);
> + tce_iommu_disable(container);
> + mutex_unlock(&container->lock);
> + return 0;
> + }
> +
> + return -ENOTTY;
> +}
> +
> +static int tce_iommu_attach_group(void *iommu_data,
> + struct iommu_group *iommu_group)
> +{
> + int ret;
> + struct tce_container *container = iommu_data;
> + struct iommu_table *tbl = iommu_group_get_iommudata(iommu_group);
> +
> + BUG_ON(!tbl);
> + mutex_lock(&container->lock);
> +
> + /* pr_debug("tce_vfio: Attaching group #%u to iommu %p\n",
> + iommu_group_id(iommu_group), iommu_group); */
> + if (container->tbl) {
> + pr_warn("tce_vfio: Only one group per IOMMU container is allowed, existing id=%d, attaching id=%d\n",
> + iommu_group_id(container->tbl->it_group),
> + iommu_group_id(iommu_group));
> + ret = -EBUSY;
> + } else if (container->enabled) {
> + pr_err("tce_vfio: attaching group #%u to enabled container\n",
> + iommu_group_id(iommu_group));
> + ret = -EBUSY;
> + } else {
> + ret = iommu_take_ownership(tbl);
> + if (!ret)
> + container->tbl = tbl;
> + }
> +
> + mutex_unlock(&container->lock);
> +
> + return ret;
> +}
> +
> +static void tce_iommu_detach_group(void *iommu_data,
> + struct iommu_group *iommu_group)
> +{
> + struct tce_container *container = iommu_data;
> + struct iommu_table *tbl = iommu_group_get_iommudata(iommu_group);
> +
> + BUG_ON(!tbl);
> + mutex_lock(&container->lock);
> + if (tbl != container->tbl) {
> + pr_warn("tce_vfio: detaching group #%u, expected group is #%u\n",
> + iommu_group_id(iommu_group),
> + iommu_group_id(tbl->it_group));
> + } else {
> + if (container->enabled) {
> + pr_warn("tce_vfio: detaching group #%u from enabled container, forcing disable\n",
> + iommu_group_id(tbl->it_group));
> + tce_iommu_disable(container);
> + }
> +
> + /* pr_debug("tce_vfio: detaching group #%u from iommu %p\n",
> + iommu_group_id(iommu_group), iommu_group); */
> + container->tbl = NULL;
> + iommu_release_ownership(tbl);
> + }
> + mutex_unlock(&container->lock);
> +}
> +
> +const struct vfio_iommu_driver_ops tce_iommu_driver_ops = {
> + .name = "iommu-vfio-powerpc",
> + .owner = THIS_MODULE,
> + .open = tce_iommu_open,
> + .release = tce_iommu_release,
> + .ioctl = tce_iommu_ioctl,
> + .attach_group = tce_iommu_attach_group,
> + .detach_group = tce_iommu_detach_group,
> +};
> +
> +static int __init tce_iommu_init(void)
> +{
> + return vfio_register_iommu_driver(&tce_iommu_driver_ops);
> +}
> +
> +static void __exit tce_iommu_cleanup(void)
> +{
> + vfio_unregister_iommu_driver(&tce_iommu_driver_ops);
> +}
> +
> +module_init(tce_iommu_init);
> +module_exit(tce_iommu_cleanup);
> +
> +MODULE_VERSION(DRIVER_VERSION);
> +MODULE_LICENSE("GPL v2");
> +MODULE_AUTHOR(DRIVER_AUTHOR);
> +MODULE_DESCRIPTION(DRIVER_DESC);
> +
> diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
> index 284ff24..87ee4f4 100644
> --- a/include/uapi/linux/vfio.h
> +++ b/include/uapi/linux/vfio.h
> @@ -22,6 +22,7 @@
> /* Extensions */
>
> #define VFIO_TYPE1_IOMMU 1
> +#define VFIO_SPAPR_TCE_IOMMU 2
>
> /*
> * The IOCTL interface is designed for extensibility by embedding the
> @@ -375,4 +376,37 @@ struct vfio_iommu_type1_dma_unmap {
>
> #define VFIO_IOMMU_UNMAP_DMA _IO(VFIO_TYPE, VFIO_BASE + 14)
>
> +/*
> + * IOCTLs to enable/disable IOMMU container usage.
> + * No parameters are supported.
> + */
> +#define VFIO_IOMMU_ENABLE _IO(VFIO_TYPE, VFIO_BASE + 15)
> +#define VFIO_IOMMU_DISABLE _IO(VFIO_TYPE, VFIO_BASE + 16)
> +
> +/* -------- Additional API for SPAPR TCE (Server POWERPC) IOMMU -------- */
> +
> +/*
> + * The SPAPR TCE info struct provides the information about the PCI bus
> + * address ranges available for DMA, these values are programmed into
> + * the hardware so the guest has to know that information.
> + *
> + * The DMA 32 bit window start is an absolute PCI bus address.
> + * The IOVA address passed via map/unmap ioctls are absolute PCI bus
> + * addresses too so the window works as a filter rather than an offset
> + * for IOVA addresses.
> + *
> + * A flag will need to be added if other page sizes are supported,
> + * so as defined here, it is always 4k.
> + */
> +struct vfio_iommu_spapr_tce_info {
> + __u32 argsz;
> + __u32 flags; /* reserved for future use */
> + __u32 dma32_window_start; /* 32 bit window start (bytes) */
> + __u32 dma32_window_size; /* 32 bit window size (bytes) */
> +};
> +
> +#define VFIO_IOMMU_SPAPR_TCE_GET_INFO _IO(VFIO_TYPE, VFIO_BASE + 12)
> +
> +/* ***************************************************************** */
> +
> #endif /* _UAPIVFIO_H */
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